High-quality Material The heated insoles are Made from soft elastic EVA polyester, offer longer durability and not easily deformed. Heating Elements Covers Full Foot Area High-quality heating elements to keep the foot at an ideal temperature. The temperature can reach up to 120 F to warm cold feet in winter without too hot to sweat. Improves blood circulation for individuals.Give you a warm winter. Ultra-thin and lightweight Light and soft design for maximum comfort. Thickness is approximately 0.16 Inch1cm. Slim design does not make your shoe any tighter or feel heavier. One size fits all Very thin heated insole that is easy to cut. You can trim the insole down to fit any foot size and any foot wear. ( US Shoes Size 5-10 ) Easy to Use Just connect it to USB port of computer, power bank, or power adapter of 5V, 1A or 2A. (no built-in battery). And comes with a 1.5 meter extension USB cable. Easy to install and remove if needed. Never have cold feet again.